Recently, with the development of mobile devices, the number of forged products has rapidly increased. Since forged products are too elaborate for even experts to identify, the losses of consumers who purchase forged products while mistaking them for genuine products are considerable. The problem with this is that it is difficult to distinguish between genuine products and forged products in terms of appearance. Although enterprise-level efforts to develop technology for overcoming the above problem have been made, effective results cannot be achieved due to problems, such as costs required for research into security technology and the application thereof, and equipment required to determine whether or not a product has been forged. Accordingly, there is urgency for the development of new security technology for dealing with the gradually increasing number of forged products.
As one of the new security technologies for overcoming the above problem, there is a technology using a moiré phenomenon. A moiré phenomenon is a phenomenon in which two regular successive patterns overlap each other and thus another pattern appears. In the field of displays, technology has been developed toward the direction in which a moiré phenomenon is prevented from occurring. In contrast, in the field of security, there have been attempts to utilize the moiré phenomenon as a new forgery prevention element. However, currently, most of these technologies have their limitations in that application targets are limited to paper media or the like, or are problematic in that their effectiveness is deteriorated due to the advent of highly precise forging techniques. As a result, there is an urgent need for the provision of countermeasures against these problems.